For a school electronics project he had to take some old device and build a modern, high tech version of it. He decided that he wanted to do something with magic and a while ago came around and had a root through my books for something that he could build. He came across an old signalling device. The original idea was that there were a number of light bulbs on a magicians table, screened from the audience's view. These were connected to switches off stage than an assistant could operate to send messages to the magician. I can't remember exactly where he found it now, in some old tome that I'd printed off the Learned Pig from the 1940s I think.

So what did he give me? A deck of cards and a little key pad of numbers. The deck of cards has got 10 little lights showing through it which can be switched on and off wirelessly from the keypad. The deck could happily sit on a magician's table without being noticed, you could probably even flash it at the audience and get away with it. I'm just looking forward to the next time I perform and can give it a test run

I was very impressed with it, I'd expected to have to smile politely when I opened it but it's really very good and very usable

Funnily enough, he's a regular little Del Boy and was asking if I thought there might be a market for it. I said that there certainly would be so he's taken away a bunch of my books to see what else he can come up with.

He's a clever lad, not much interest in magic but loves inventing little gadgets so it'll be interesting to see what else he comes up with.